The subject matter disclosed herein relates to brushless synchronous machines.
In a brushless synchronous machine, such as a synchronous generator, a regulator delivers the field excitation to the rotating field poles. An increase or decrease in the field current to the regulator affects the generator field voltage (main field voltage). The field current that affects the main field voltage is controlled by a feedback loop, but the resulting main field voltage may not be conveniently measurable due to rotation of the field. As a result, a fault in the feedback loop or the system (gird) may cause the field current and, consequently, the main field voltage to exceed rated values.